To measure the scattering parameters (S-parameters), such as S11, S12, S21 and S22, of a device under test (DUT) with a non-coaxial interface, the DUT is typically installed in a test fixture having a coaxial interface. Such test fixtures are not electrically transparent. Consequently, the test fixture must be characterized to determine its S-parameters so that the S-parameters of the test fixture can be de-embedded from the measurement results to determine the S-parameters of the DUT itself.
Determining the S-parameters of the test fixture with accuracy and repeatability sufficient not to impair the accuracy and repeatability of the S-parameters of the DUT has proved to be challenging in practice.
Accordingly, what is needed is a way to determine the S-parameters of a test fixture used to measure a device under test having a non-coaxial interface with an accuracy that does not impair the accuracy with which the S-parameters of the DUT can be determined.